Iphone se problems

Still on iOS 12?

I have a passion and hobby to go through complete literature and review of all iOS releases and needless to say I haven't missed iOS 12.1.3, 12.1.4 12.2, 12.3 & 12.3.1 assessment published on various news media and on Apple web page including leading news magazines (Forbes & Fortune Magazines).

The major takeaways from this iOS 12.3 update is Apple TV, Kids TV, The app is available on Samsung TVs, tvOS has been updated, AirPlay 2, Apple TV app,

And iOS 12.3.1 includes bug fixes for your iPhone and iPad. This update:

• Fixes an issue that could prevent making or receiving VoLTE calls
• Fixes issues in Messages that could cause messages from unknown senders to appear in your conversation list even though Filter Unknown Senders is enabled
• Fixes an issue that could prevent the Report Junk link from appearing in Messages threads from unknown senders
• 
  

No where I could find any link on the problem of "Battery Drain" faced by you. Introspect and have a complete and thorough check on the way you handle settings on your iPhone.

Read often for a peaceful life.

Solution. https://discussions.apple.com/docs/DOC-250000677

If your issue was just performance related I would suggest looking at Battery Health and is it close to 80%, but you also say the device is experiencing connectivity problems which may indicate some form of Update corruption.

How did you do the last update, was it via OTA or with iTunes, if the former I would try a Restore.

Restore your iPhone, iPad, or iPod to factory settings - Apple Support

You can use a BackUp to get your configurations and content back but just be aware that it may “import” the issue back again, that’s why Apple recommends setting up as “New”, if your stuff is in iCloud most of it should sync back anyway.

If you are not happy with a Restore you could try “Reset All Settings” from Settings>General>Reset which will not remove content but does remove all user configurations but if your problem is within the OS itself a Reset will not resolve for obvious reasons.

Also don’t forget a Force Restart, it can clear up some glitches but I feel in your case you may have too many things going on, but it’s quick and easy to try so worth ago.

Force restart iPhone - Apple Support

Hope some of this helps.